Field notebook
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Field notebook
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Permanent editions
Published facts keep their original date, evidence and correction trail. Drafts and withdrawn editions are never mixed into this index.
Common poorwills enter torpor lasting weeks in rock crevices, letting body temperature fall far below normal. A bird found in California in the 1940s was recorded in the same crevice across successive winters, the first documented case in any bird.
Female Cairns birdwings lay eggs on the introduced Dutchman's pipe, mistaking it for a native host. The vine smells right and triggers the same egg-laying response, but its chemistry kills the caterpillars that hatch on it.
A beluga sturgeon can take fifteen to twenty-five years to mature, then spawns not annually but at intervals of several years. That reproductive schedule, combined with fishing for caviar and dammed rivers, is why the species collapsed so fast.
Across all 3,000-plus described centipede species, the count of leg-bearing segments is always odd, ranging from 15 pairs to 191. Even numbers do not occur, and 100 legs, the name notwithstanding, is impossible.
The male European stag beetle's mandibles are the most conspicuous jaws of any European insect. Lengthening a jaw does sacrifice leverage, but males pay for it with an enormously enlarged head, and measurements show they still bite harder than females, not softer.
Its famous resilience is not a property of the active animal. A tardigrade withstands extremes only after entering a tun state, losing most of its body water and suspending metabolism, and an active hydrated tardigrade is easy to kill.
The name has nothing to do with the shell, which is usually brown or olive with darker streaks. It comes from the greenish fat under the carapace, a colour that follows from a nearly unique adult diet of seagrass and algae.
A sawfish looks like a shark with a hedge trimmer on its face, but its gill slits are on the underside of the body and its pectoral fins are fused to the head. Those are ray characters, and sawfishes sit within the rays, not the sharks.
Water drawn in at the front passes through an internal mucus net that catches plankton, then is expelled at the rear as jet propulsion. Feeding and locomotion are one action, driven by rhythmic contraction of muscle bands.
A loggerhead that has never seen the open ocean can still steer within it. Laboratory work shows hatchlings change swimming direction when placed in magnetic fields copied from specific points along their migratory circuit, as though reading position rather than only heading.
It does not dig a burrow that stays open. The animal pushes forward through loose sand and the tunnel collapses behind it, so it leaves no permanent structure, which is one reason it is so seldom found.
A vervet's leopard alarm sends the troop into trees, its eagle alarm makes them look up and take cover, and its snake alarm makes them stand and scan the ground. Playback experiments in the 1970s showed the calls alone produce the responses.
This small shark uses its muscular paired fins to stride over exposed coral between tide pools, and it tolerates the oxygen crash those pools suffer at night by shutting down parts of its brain rather than dying.
Hunting rodents under snow, a fox listens, rears up and dives nose-first into the drift. A widely reported study suggested the pounces are more successful when aimed roughly north-east, but that finding remains unreplicated.
The last free-living European bison was shot in 1927. The species survived only in zoos and private parks, and the entire population now running in European forests traces back to a dozen founders whose pedigrees were recorded by hand.
Dungeness crabs are periodically unsafe to eat, not because of anything the crab does, but because a bloom of the diatom Pseudo-nitzschia loads their viscera with domoic acid. Managers have delayed entire seasons on the strength of toxin tests.
Among the best swimmers of any primate, proboscis monkeys cross Bornean rivers by plunging in from overhanging branches. Their hind feet carry partial webbing between the toes, and they can travel underwater for stretches of tens of metres.
Repeated DNA testing of restaurant and retail samples in the United States has found that a large share of fish labelled red snapper belongs to other species entirely, making it one of the most consistently mislabelled seafood names.
Brown-headed cowbirds lay in the nests of hundreds of songbird species and most accept the foreign egg. The grey catbird is a strong rejecter, recognising the egg and puncturing or removing it before incubation is well under way.
For decades the dragon's lethality was blamed on filthy mouths seething with bacteria. Anatomical and chemical work published from 2009 onward instead found true venom glands in the lower jaw, secreting proteins that lower blood pressure and hinder clotting.
Romans brought fallow deer to Britain and bred them at places like Fishbourne, but the population did not outlast Roman rule. The deer in British parks today trace to a second, Norman-era introduction from the eastern Mediterranean.
Motmots swing the racquet-tipped tail from side to side like a pendulum. Field experiments indicate the display is directed at predators, signalling that the bird has detected them, rather than at other motmots.
The barb is not a bone or a tooth grafted onto the tail. It is an enlarged dermal denticle, the same structure that gives shark skin its sandpaper texture, sheathed in tissue that produces the venom and shed and regrown through life.
Brazilian hospital series covering thousands of Phoneutria bites find that the great majority produce local pain and nothing more. Severe envenoming appears in well under one per cent of cases, concentrated in young children.